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system dynamics
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Major: System Dynamics
Slide show brought to you by:
WPI Social Science & Policy Studies And
WPI System Dynamics Club
Author: David Liu
Basic System Behaviors
Exponential Growth
Goal Seeking
Oscillation
S-shaped Growth
S-shaped Growth with Overshoot
Overshoot and Collapse
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Exponential Growth
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System Level
Inflow
Net increase rate
Positive feedback loops generate growth, amplify deviations, and reinforce change.
Goal SeekingNegative feedback loops seek balance, equilibrium, and stasis.
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System LevelCorrective Action
Discrepancy
GoalRate of change
OscillationTime delays cause the state of system to constantly overshoots its
goal or equilibrium state, reverses, then undershoots, and so on.
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System LevelCorrective Action
Discrepancy
Perception
GoalRate of change
Perception Delay
S-shaped GrowthNo real quantity can grow (or decline) forever, eventually one or
more constraints halt the growth.
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System LevelNet Increase Rate
Resource Adequacy
Carrying CapacityNormal Growth Rate
S-Shaped Growth with OvershootTime delays in lead to the possibility that the state of the system
will overshoot and oscillate around the carrying capacity.
System LevelNet Increase Rate
Resource Adequacy
Carrying CapacityNormal Growth Rate
Delayed Resource Effect
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Overshoot and CollapseThe ability of the environment to support a growing population is
eroded or consumed by the population itself.
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System LevelNet Increase Rate
Resource Adequacy
Erosion of Carrying Capacity
Normal Growth Rate
Carrying Capacity
Consumption rate
Applications of System Dynamics• Constructing better mental models• Simulating & experimenting with computer models• Use the same engineering tools to experiment with
and to solve many messy problems of:– Management
– Government
– Economy
– Environment
– Other dynamic systems
